Method and devices for the determination of colors and color tolerances in a visual manner in any kind of artificial light or sunlight

ABSTRACT

Color evaluation of a color sample is effected by producing in a simultaneous field of vision a plurality of separate color comparison regions each differing in color slightly from one another and juxtaposed with a multiplicity of images of a single small area of a color sample. The color of the sample images can be compared simultaneously with the colors of the comparison regions and a color attribute of the comparison regions varied until visual correspondence is obtained between the sample color and one of the comparison regions.

United States Patent Piringer 15] 3,653,771 I 51 Apt. 4, 1972 [54]METHOD AND DEVICES FOR THE DETERMINATION OF COLORS AND COLOR TOLERANCESIN A VISUAL MANNER IN ANY KIND OF ARTIFICIAL LIGHT OR SUNLIGHT FritzPiringer, Stiege i0, 13 Graf Starhemberggasse, Vienna, Austria Filed:Oct. 29, 1969 Appl, No.: 872,427

inventor:

Related US. Application Data [63] Continuation of Ser. No. 262,985, Mar.5, 1963.

[30] Foreign Application Priority Data Mar. 8, 1962 Austria ..A 1924/62us. on ..356/194, 35/283, 356/195 1m. Cl ..G0lj 3/46 Field oiSearch..356/173,174,178,191,194, 356/195; 35/283; 88/1 M1, 1 P, 14 C, 14 CB,14

CC, 14 CN, 14 VC, 14 E, 14 R, 23 C, 73, 74, 84,

[56] References Cited UNITED STATES PATENTS 1,597,830 8/1926 Rueger..356/194 2,649,017 8/1953 McCarty ..356/175 2,684,010 7/1954 Bukkiey..356/192 Primary Examiner-Ronald L. Wibert Assistant Examiner-J.Rothenberg Attorney--Waters, Roditi, Schwartz & Nissen [5 7] ABSTRACTColor evaluation of a color sample is efiected by producing in asimultaneous field of vision a plurality of separate color comparisonregions each differing in color slightly from one another and juxtaposedwith a multiplicity of images of a single small area of a color sample.The color of the sample images can be compared simultaneously with thecolors of the comparison regions and a color attribute of the comparisonregions varied until visual correspondence is obtained between thesample color and one of the comparison regions.

26 Claims, 26 Drawing Figures PATENTEDAFR 4 I972 3,653,771

sum 1 or 4 PATENTEDAPR 4|912 SHEET 2 [IF 4 PATENTEUAPR 4 I972 SHEET 3[IF 4 METHOD AND DEVICES FOR THE DETERMINATION OF COLORS AND COLORTOLERANCES IN A VISUAL MANNER IN ANY KIND OF ARTIFICIAL LIGHT ORSUNLIGHT This is a continuation of application Ser. No. 265,985 filedMar. 5, 1963.

This invention relates to a method and devices for the determination ofcolors, particularly of non-self-luminous objects. Such objects aredivided into the following groups:

a. Transparent objects (solid, liquid, gaseous) whose colors aredetermined in transmitted light.

b. Opaque objects (solid, liquid, gaseous) whose surface is tested andwhose color and/or gloss is determined in incident (reflected) light atdefined angles.

c. All those objects of groups (a) and (b) above, which, in addition,produce a characteristic color phenomenon (a socalled fluorescent color)under special illumination (e.g. ultraviolet light), which is differentfrom their appearance in normal light.

The colors of all objects of groups (a), (b) and (c) can be compared anddetermined, and it is an object of the invention to provide a method andmeans for attainingthis result.

Heretofore no adequate means for measuring colors have been available tolarge sectors of industry, the arts and commerce, where color isprocessed as a raw material, where colorations are carried out, or wherethe natural color of substances or objects is merely observed andcritically evaluated as a feature of quality of the substance or object.Physical methods for measuring colors have been in existence for 50years and since 1931 there has been available the internationallyrecognized color system of the International Commission on Illumination(C.l.E.). This system, however, can only be employed at institutes,since very sensitive and costly apparatus and scientifically trainedoperating personnel are required. The location of a particular color inthe OLE. system must be computed from the results of a number ofphysical measurements. For practical purposes, in the workshops andfactories with highly vibrating machinery, such expensive, sensitiveapparatus cannot be used; moreover, the evaluation of the results ofmeasurements is time-consuming.

Photoelectric colorimeters with selenium-cells and a variety of filtershave been commercially available for about 40 years. Chemists employsuch colorimeters, for instance, for determining the concentration ofsolutions by taking the occurring changes of absorption as clues. Thecolorimeters are calibrated with standard solutions of knownconcentrations and can thus be used for determining the unknownconcentration of the solution under investigation. It is theconcentration rather than the color that is measured in this case, sincecolor is only the means and not the end of the measuring process.Certain colorimeters, however, can be especially modified for themeasurement of colors. Strangely enough, these devices, however, are notvery popular.

Since the eye is the most sensitive instrument for measuring chromaticcolors, it is an object of the invention to provide a device which iseffective in making a color determination utilizing visual perception.

There are a few visual photometers still in use today, some of which canbe adapted for color measurement by means of filters, but these are alldesigns of decades ago, and they do not meet the requirements which haveto be established in order to provide optimal conditions as well as meetthe considerations relating to color psychology, since a great varietyof factors interact and the human visual apparatus can adapt to a largedegree to external conditions.

Even today color charts are used as an expedient, on which primary andmixed colors are arranged according to one of the many color systems;e.g. the standard color charts of the British Colour Council, colorcharts according to Ridgeway, Baumann-Prase, Pope, Syreeni, the ColorDictionary by Maerz & Paul, the RAL-Color Card, color charts accordingto Leisser, l-lickethier, Johannson, Resselgren, Ostwald, Munsell andrecently according to DIN 6164. Individual firms still produce their owncharts or color samples, which, due to the lack of a universallyrecognized nomenclature, are referred to by delivery numbers orfrequently only by fancy names. Without a color sample it is stillimpossible today to determine a color or to order a color, for instanceby telephone. ln their systematic set-up the individual color chartsstart from different bases and there is practically no relationshipbetween them.

In everyday practical work, it is hardly possible to achieve anabsolutely exact match of a given color sample (i.e. the impossibilityto differentiate between sample and match). lrregularities and qualityfluctuations in the raw materials, between the various stages ofmanufacture and finishing (printing, dyeing, etc.) are never completelyavoided, and there is a great need for providing a standard forpermissible color deviations (tolerances), their extent varyingaccording to material,

' processing techniques and price.

The fact that in the field of colors no generally valid tolerances havebeen agreed upon as yet is mainly due to the lack of adequate simpletools for the practical control of such color tolerances. The problem isfurther aggravated by the fact that one single measured value does notsuffice for the specification of a color. Three different attributes(characteristics) are necessary and all color systems operate with threequantities, e.g., hue, whiteness, and darkness stage.

Color is three-dimensional. For establishing permissible color deviation(color tolerances) two limiting values are required for each of thethree color attributes, making a total of six limiting values. Thesevalues define a three-dimensional range of color tolerances, i.e. acolor space in whose center the specified color is located. So far nodevice has been available for a continuous realization of such a colortolerance range in which these tolerance colors are seen altogether! Oneconsiderable disadvantage common to all presently known devices for thedetennination of color is that in their respective fields of visionalways a single comparison color was shown beside one sample colorareas.

It is accordingly a further object of the present invention to provide amethod and means by use of which the determination of colors and colortolerances may be achieved in a visual manner in any kind of artificiallight or sunlight. According to the invention, a number of variablecomparison color fields, which differ only slightly in color, arepresented simultaneously, preferably as multiple images (e.g. nine) ofone and the same spot of the sample being produced. The sample color isshown bordering on said comparison color fields sharply and withouttransition, whereby a simultaneous field of vision with individual,separate color comparison places is produced. The colors of thecomparison color fields are changed successively, by changing the colorsas well as by regulating the incident light of the three known colorattributes, preferably one being changed jointly for all comparisoncolor fields. The second and third attributes are changed preferablyonly within the zone and/or group divisions of the field of vision asare assigned to them. A given sample color is first examined as tovisual correspondence at a coarse-matching place, which is preferablylocated centrally in the simultaneous field of vision, following whichthe degrees of visual deviation are compared at the individual,preferably peripherally located finematching places. The setting isagain adjusted until finally the remaining deviations, reduced to theattainable minimum, are perceived to be of equal extent. The complianceor non-compliance with the three-dimensional tolerance range agreed uponfor a given sample color is determined by evaluating the kind anddirection of the deviation of the sample color fromthe values specifiedfor it. When the color tolerance range has been complied with, colorcontrasts of slight to moderate strength and of varying direction willbe observed in the simultaneous field of vision. Increasingly strongercontrasts of uniform direction will be observed when one of the limitingcolors of the tolerance zones of the three color attributes-usuallyagreed upon in varying widths for each of thern-has been exceeded.

Hence it follows that we are concerned here with the entirely novel typeof multi-color field of vision; a simultaneous field of vision. A samplewhich is seen for instance ninefold is simultaneously seen with ninedifferently colored comparison color fields-altogether there are 18color areas simultaneously present in the field of vision in this case.By means of multiple image formation, the sample is simultaneouslyconfronted with any desired number of variable comparison colors. Itmust be stressed at this point that it is not a number of differentspots of the sample that are represented, but several like images of oneand the same spot of the sample are produced at different places bysimultaneous transposition. The distances of transpositions, number offields, proportions of areas, form, size and selection of color of suchsimultaneous fields of vision can b modified to suit widely differentpurposes. Colored simultaneous fields of vision can be realized in agreat variety of special designs for vision tests, contrast and harmonytests.

Examples of simultaneous fields of vision are given in the drawings, inwhich the samples are designated by the letter P, and the comparisoncolor fields by small letters.

FIG. 1 shows a ninefold simultaneous field of vision in its simplestform as an arrangement of nine small squares in a sample color area.

FIG. la shows the same arrangement, covered with a surrounding fieldmaskwhich has circular openings;

FIG. lb shows an arrangement of circular surfaces within a circularsample color area;

FIG. 2 represents adjacent squares with circular apertures which revealthe sample color;

FIG. 2a shows the same arrangement as FIG. 2, but illustrates colordifferences by different hatch lines;

FIG. 2b illustrates color differences in the sample color fields;

FIG. 3 shows a simultaneous field of vision with horizontally continuouscomparison color fields;

FIG. 3a illustrates the arrangement of comparison color fields andsample color fields in a desired pattern;

FIG. 4 represents the application of the principle of simultaneity to atype of design which is used for the purpose of color vision testing;

FIG. 5 shows a division of a simultaneous field of vision intoconcentric zones;

FIG. 5a shows the division of a simultaneous field of vision intosectors;

FIG. 6 is a perspective view of a multiple light-deflecting element withreflecting, slightly inclined surfaces;

FIG. 7 is a perspective view of a multiple of light-deflecting elementswith refractive surfaces;

FIGS. 6a and 7a represent a simultaneous field of vision in its simplestform, produced by a colored e. g. printed) surface having openingstogether with a multiple light-deflecting element;

FIG. 8 is a perspective view of a multiple light-deflecting element byway of example in combination with an inclined plane surface;

FIG. 9 shows the inverse design of a multiple light-deflecting elementwith totally reflecting surfaces;

FIG. 10 represents a multiple discontinuous, preferably specularsurface, with inclined and/or tapered bores;

FIG. 11 is a perspective view of the schematic structure of a path ofrays for a device for the determination of colors;

FIG. 12 shows a round, multiple light-deflecting element in plan viewand in section along line A-B;

FIG. 13 shows a multiple, discontinuous, preferably specular surface,for producing a simultaneous field of vision as shown schematically inFIG. 1;

FIG. 14 shows a multiple, discontinuous, preferably specular surfacetogether with a central reflector, which is mounted on a transparentbody;

FIG. 14a shows a multiple, discontinuous, preferably specular surfacewhich serves at the same time as carrying agent and whose inner edgesare tapered;

FIG. 14b is an enlarged view of the central reflector shown in FIG. 14;FIG. 15 is a perspective view of two possible embodiments of multiple,discontinuous, preferably specular surfaces, that shown in dotted linesrepresenting two known photometer prisms which have masks in front ofeach of their short sides, while the hatched surface represents acheaper design with a set of glass plates instead of the expensiveprisms; and

FIG. 16 is a perspective view of the principal design of a multiple,discontinuous surface consisting of a specially treated and an untreatedprism.

It has been noted hereinbefore that color can be defined in terms ofthree attributes namely, hue; whiteness or saturation; and blackness ordarkness stage. The variation of the three attributes determines theresulting color.

The color appearance of a simultaneous field of vision is illustrated bythe following example in relation to FIGS. 1 and 2:

EXAMPLE I a b c light orange-red orange-red deep orange-red lightcarmine-red Carmine-red deep carmine-red g h i light purple-redpurple-red deep purple-red Assume that horizontal zones show the samehue. The vertical zones are assigned to the zones of saturation. Thecentral comparison color field e corresponds to the desired color, i.e.,

the specified color. The hue of field d is less saturated than field e,that of field f is more saturated than the specified color in e. Thecolor of field b is more yellowish, that of field h is more bluish thanthe specified color carmine-red of field e. The corner fields showdeviations in two directions from that of field e: field a is moreyellowish and less saturated, field g is more bluish and less saturated.Field c is more yellowish and more strongly saturated, field i is morebluish and more strongly saturated.

The multiple light-deflecting elements necessary for simple devices forthe application of the method are represented in FIGS. 6, 6a, 7, 7a, and12. They have a number of surfaces 42a to 42i, 49a to 49i and 58respectively, which are slightly inclined towards one another andarranged side by side and cause convergence of the beams incident uponthem. Surfaces 42a to 42i preferably are surface mirrors, whereassurfaces 49a to 49i and 58 respectively are prismatic zones of a bodywith refractive properties. In addition to a convergence of beams, thelight-deflecting elements according to FIGS. 6, 8 and 9 also cause acommon change in direction of all beams (e.g. at a right angle), whereaslight-deflecting elements according to FIGS. 7 and 12 respectively donot change the straight-lined path.

For the purpose of the most simple method of a visual simultaneouscomparison of colors, a multiple light'deflecting element 49 (FIG. 7) isprovided with a handle (not shown) similar to the handle of a magnifyingglassand a color chart 50 with openings 51 (FIG. 7a) is placed directlyon the upper side of the multiple light-deflecting element 49, e.g. byinserting it into a small frame. Exactly in the manner of handling amagnifying glass, the multiple light-deflecting element 49, togetherwith the color chart placed on it, is held over the sample and itsvertical height is varied in small degrees until homogenous anduniformly colored images of one spot of the sample are visible in theopenings 51. At one glance it can be judged which of the fields of thecolor chart comes closest to or is equal to the sample color. For thepurposes of frequently checking colorations, e.g. in commercialenterprises, color charts indicating the permissible color deviations ortolerances can be used. By this arrangement deviations in two directionscan be checked. By way of example, for the checking of a carmine-redcolor the color chart fields of color chart 50 (FIG. 6a and 7a) arearranged according to example I described above. On the basis of thissystematic arrangement the direction and approximate degree of a colordeviation can immediately be ascertained. A possible difference inbrightness between the sample and the color chart can be compensatedwithin certain limits by a slight turn away from the light, of themultiple light-deflecting element, or merely by turning the color chart.If larger differences in brightness are involved-also called differencesin the degree of darkness the color chart must be replaced.

If the method as described above is carried out with optical comparisoncolor fields to replace the color charts, so that by adding furtherparts, the multiple light-deflecting element'is expanded into a moreelaborate device, additional possibilities for application result.

All apparatus for visual comparison so far in existence had bipartitefields of vision. By the simultaneous field of vision the principle ofthe present invention differs basically from the prior art, since eachsetting is simultaneously judged as to equality (visual correspondence)and multiple neighboring color contrast. Due to the simultaneouspresence of a number of different colors the eye is also prevented to alarge extent from undergoing the known phenomenon of chromatic adaption.

In substance, a device for carrying out the method for determining in avisual manner colors and color tolerances in any kind of artificiallight or sunlight in accordance with the present invention comprises anumber of movable diaphragm plates and one immovable diaphragm platehaving transparent as well as opaque areas, said diaphragm plates beingarranged in the path of rays of any desired light source, for instance,at the front of a casing of the device. The transparent areas of theimmovable diaphragm plate can be covered alternately and to varyingdegrees by the opaque areas of the movable diaphragm plates by movingsaid diaphragm plates. The diaphragm plates are provided with scaleparts, scale divisions and reading marks preferably placed directlythereon. In the interior of the casing each transparent area of theimmovable diaphragm plate is assigned one light-deviating unit, whichunits are directed towards the test color surfaces or the sample in asample holder. The chromatic test color surfaces are jointly assignedone of the commonly known optical devices for the mixing of light,preferably a set of glass plates, whereas each of the neutral-gray testcolor surfaces is assigned one of the commonly known optical devices forthe mixing of light, preferably a set of glass plates, each. For bendingthe paths of rays commonly known deviating mirrors are provided. Amultiple light-deflecting element together with a multiplediscontinuous, preferably specular surface produces the simultaneousfield of vision, which is seen through an eyepiece.

A simultaneous field of vision in accordance with the present inventionoffers the possibility of introducing comparison color fields in otheroptical instruments (e.g. telescope, microscope, medical examinationapparatus such as endoscopes, etc.) without thereby losing too much ofthe size of the field of vision of the instrument.

The mode of operation of one possible device in accordance with thepresent invention is as follows:

As can be seen from FIG. 11, three diaphragm plates 2, 3, and 4, whichare arranged one after the other and are pivoted on a common center, areplaced in the path of a light source 1. The fourth diaphragm plate 6 ismounted so as to be immovable. The diaphragm plates 2, 3, 4, and 6 areof glass and are each provided with a photographic layer. The immovablediaphragm plate 6 is blackened (opaque) over its entire surface and hastransparent areas 7, 8, 9, 10, and 11 as well as with the reading window12 with reading mark 13. The transparent areas 7, 8, 9, 10, and 11 andthe reading window 12 correspond to the openings in a casing (notillustrated) through which the light can pass into the interior in thedirections of arrows 22, 23, 24, 25, 26 and 44.

The movable diaphragm plates 2, 3, and 4 are transparent almost overtheir entire surfaces (without photographic layer) and are blackenedonly (opaque) at a few special places. Diaphragm plate 2 possesses theopaque area 14 and a scale 15. It is important that the scale occupy aprecise, fixed relation with the opaque area. For this purpose theopaque area 14 and the scale 15 are applied to plate 2 by a photographicprocess; the diaphragm plate 3 has the opaque area 16 and a scale 17photographically applied with said opaque area; the diaphragm plate 4has two opaque areas 18 and 19, as well as a scale 20 photographicallyapplied with said opaque areas 18 and 19.

Depending on the position of the diaphragm plates 2, 3, and 4 thetransparent areas 7, 8, 9,10, and 11 of the immovable diaphragm plate 6are either completely, partly or not at all eclipsed by the opaque areas14, 16, 18, and 19 of said diaphragm plates. The arrangement willsuitably be such that the transparent area 7 remains free when thetransparent areas 8 and 9 are eclipsed by the opaque areas 18 and 19.Conversely, the transparent areas 8 and 9 remain free as soon as theopaque area 18 begins to eclipse the transparent area 7. Thus thediaphragm plate 4 with the opaque areas 18 and 19 alternately covers thetransparent areas 8 and 9 together or the transparent area 7 alone. At acertain position (Zero) no one of the transparent areas 7, 8 and 9 areeclipsed and the light can pass simultaneously through all saidtransparent areas.

Contrary to the above is the interaction between the opaque area 16 andthe transparent areas 10 and 11. At a certain position (zero on thescale of the diaphragm plate 3) both transparent areas 10 and 11 areentirely eclipsed by the two ends of the opaque area 16 of the diaphragmplate 3. If the diaphragm plate 3 is moved in a clockwise direction, theopaque area 16 is removed from the transparent area 10 and thus thelight is allowed to pass in the direction of the arrow 24. Thetransparent area 11, however, remains eclipsed. If the diaphragm plateis moved in the opposite direction, the opposite end of the opaque area16 releases the transparent area 11 for the passage of light in thedirection of the arrow 25. The diaphragm plate 3 with the opaque area 16thus covers the transparent areas 10 and 11 alternately orsimultaneously.

In addition to diaphragm plate4, diaphragm plate 2, whose opaque area 14alternately covers transparent areas 8 and 9, affects transparent areas8 and 9. At a certain position (zero of the scale) of the diaphragmplate 2 the transparent area 8 is free and the transparent area 9completely eclipsed. When the diaphragm plate is moved in a counterclockwise direction the opaque area 14 increasingly covers thetransparent area 8 and at the same time releases an equally largeportion of the transparent area 9.

For the purposes of comparing the sample color 36 with the test colorsurfaces 32, 33, 34, and 35, a path of rays is directed in such a waythat all these areas can be viewed simultaneously when locking throughthe ocular or eyepiece Oc.

To this end set of glass plates 37 is interposed between test colorsurfaces 32 and 33, a set of glass plates 38 is disposed for (mirror-)reflecting of the test color surface 34, a set of glass plates 39 for(mirror-) reflecting of the test color surface 35 and two mirrors 40 and41 are arranged for bending the ray path.

Furthermore, a multiple discontinuous surface 43 is placed in the pathof rays of the sample, by means of which the path of rays of the testcolors is combined with the path of rays of the sample, said surface 43having openings through which the individual bundles of rays of themultiple light-deflecting element 42 (or, in the case of linearlycontinued path those of a multiple light-deflecting element 49) comingfrom sample 36 or 36' are viewed.

If the test color surface 32 is coated with, for instance, three verypure, intensive hues (test colors), these colors, e.g. ORANGE-RED,CARMlNE-RED, PURPLE-RED -according to FIG. 2 and example I above appearluminous and intensive whenever the transparent area 8 of the immovablediaphragm plate 6 is fully opened; the full quantity of light can enterthe casing through the diaphragm in the direction of the arrow 22 and isdirected by the light-deviating unit 27 onto the test color surfaces.When by turning the diaphragm plate 4 the transparent area 8 isincreasingly eclipsed by the opaque area 18 of the diaphragm plate,these colors appear increasingly darker and finally (when thetransparent area 8 is completely covered) black.

The same procedure also applies to the second test color surface 33 withits respective transparent area 9, direction of arrow 23, and thelight-deviating unit 28.

For reasons of expedience three pure and intensive hues (test colors)e.g. adjacent hues of the known 24-step color circle will be chosen alsofor test color surface 33. For instance, the hue steps ORANGE-RED 6,CARMINE-RED 8 and PUR- PLE-RED for the test color surface 32 and the huesteps RED 7, CARMINE 9, and PURPLE l l for the test color surface 33.

When the transparent area 8 is fully open (and thus the transparent area9 completely eclipsed by the opaque area 14.

of the diaphragm plate 2), only the test colors of the test colorsurface 32 (in the example orange-red 6, Carmine-red 8 and purplered 10)are fully illuminated and visible in the path of rays in their fullstrength.

If now, the diaphragm plate 2 is moved, the transparent area 8 iscovered just as much as transparent area 9 is exposed by opaque area 14.Thereby a continuous reduction of the illumination of test color surface32 and, simultaneously, a correspondingly increasing illumination oftest color surface 33 is caused. Simultaneously with the directly viewedhues ORANGE-RED 6, CARMINE-RED 8, and PURPLE-RED 10, the hue RED 7,reflected in increasing strength and superimposed via the set of glassplates 37, is presented in the path of rays at the time place andtogether with the ORANGE-RED 6 theretofore visible, so that both colorsensations are perceived optically blended, depending on how large theshare of one color is in relation to that of the other one. Assuming thecase, that transparent areas 8 and 9 are half opened each, the two testcolor groups are each illuminated by half the quantity of light and mixinto the intermediate hues ORANGE-RED 6.5, CARMlNE-RED 8.5, andPURPLE-RED l0.5.

By this continuous regulation with diaphragm plate 2 all intermediatesteps, or rather all intermediate colors, between the two test colorgroups 32 and 33 can be optically mixed.

Independently of the mixing of hues black can be added, in the mannerdescribed above, by means of diaphragm plate 4 so that the intermediatehues ORANGE-RED 6.5, CAR- MINE-RED 8.5, and PURPLE-RED l0.5, mentionedabove can at the same time be progressively darkened until they appearblack.

In addition to the mixing of hues with one another into pureintermediate hues and the darkening into black as described above, athird variation is provided forzthe desaturation of hues by means ofoptical adding of white.

As illustrated in FIG. 11 an additional set of glass plates 38 is placedin the path of rays. The bundle of rays in the direction of the arrow24, which passes the transparent area 10 of the immovable diaphragmplate 6 and strikes the lightdeviating unit 29, illuminates the testcolor surface 34 which is provided either with a white test surface orwith plural band gray scale (e.g. one band each of white, light-gray andmedium-gray). The image of this gray scale when the transparent area 10is exposed (this is done by turning diaphragm plate 3) is superimposedon the image of the hues (of test color surfaces 32 and 33), visible inthe path of rays, by way of the set of glass plates 38, whereby,depending on the luminous intensity of light in the direction of thearrow 24, said colors appear optically diluted, i.e. desaturated byvarying degrees.

The simultaneous field of vision viewed in the eyepiece can thus bemodified in the following manner:

1. Variation of the visible test colors by changing the hues.

2. Variation of the color sensation produced by the visible test colorsby optically mixing one test color group 32 with the other 33 intointermediate hues by means of diaphragm plate 2.

3. Variation of saturation (admixture of white) by means of thediaphragm plate 3.

4. Variation of darkness (admixture of black) by means of the diaphragmplate 4.

Compared with example I above the first possibility for modification(changing the hues) produces a simultaneous field of vision for exampleof the following appearance:

As compared to example I, the second modification (color mixing)produces a simultaneous field of vision of the following appearance:

EXAMPLE III a b c light orange-red 6.5 orange-red 6.5 deep orange-red6.5 d e carmine-red 8.5

h purple-red l0.5

light Carmine-red 8.5 deep carmine-red 8.5

g I light purple-red l0.5 deep purple-red l0.5

The third possibility for modification (degree of saturation) producesthe following:

EXAMPLE IV a b c pale orange-red 6 light orange-red 6 orange-red 6 d e flight carmine'rcd 8 carmine-red 8 h light purple-red l0 pale Carmine-red8 8 i pale purple-red IO purple-red 10 The fourth possibility formodification (degree of darkness) produces the following:

EXAMPLE V a b c dull orange-red 6 broken orange-red 6 dark orange-red 6dull carmine-red 8 broken carminered 8 dark carmine-red 8 broken purplered I0 I fiullpurple-red 10 dark purple-red 10 These few examples showthat, in effect, the multiplicity of colors in all their shadings can beadjusted and for the first time changed simultaneously andsystematically in groups.

In practice, the central color e will be adjusted to chromatic equalityas in a known equality with the sample image P method The colors visibleat the periphery will be very similar in color to the sample image P,but not fully equal to it. The degree of inequality is to be perceivedas to be of equal extent in all peripheral comparison color fields,whereas, in the case of chromatic equality in the central comparisoncolor field, the line of demarcation between said comparison color fieldand the sample field begins to disappear.

In this novel manner each setting is judged at the same time as tochromatic equality (visual correspondence) and simultaneous neighboringcolor contrast whereby measuring conditions are greatly improved. Theeye is offered, so to speak, points of reference around the desiredcolor and by this optical comfort is provided with optimal workingconditions.

The principle set forth herein lends itself to an extraordinarily greatnumber of modifications and embodiments. Thus, for instance, a surfaceresolved into color dots, accord ing to the principle of thepseudo-isochromatic charts, like FIG. 4, can be used in order todetermine exactly the degree of color sense-deficiency. The surface ofthe simultaneous field of vision is executed in pseudo-isochromaticcolors and is then adjusted to maximum admixture of white. The patientis seated in front of the device and perceives a white surface.Subsequently, white admixture is gradually reduced until the individualcolor dots emerge as from a fog. The pseudoisochromatic test figure isfirst perceived quite dimly as 48 and only when the admixture of whiteis further reduced, the correct, single-colored FIG. 13 will berecognized. From the readings which are taken, the first time whensomething becomes dimly visible at all and the second time when finallythe colors, being progressively intensified, are clearly distinguished,true color perception can be exactly diagnosed, above all in those casesin which the chart methods in use up to now are not adequate and whereanomaloscope examinations reveal anomalous trichromatism.

FIGS. 12-15 show various arrangements whereby the different simultaneousfields of vision can be obtained.

In FIG. 12 is shown a refractive multiple light deflecting element 57with slightly inclined planar surfaces 58 arranged in annular arraytherein for producing a simultaneous field of vision as shown in FIG.1b.

FIG. 13 shows a metal plate 59 with openings and a covering mask 60 forproducing the simultaneous field of vision as shown in FIG. 1. As seenin FIG. 14, the plate 59 is mounted above a transparent body 61 by beingretained in a block 63 which is secured to body 61. A tapered reflector62 is centrally disposed within the plate 59 and is mounted in body 61by pin 62b. The upper surface of the plate 59 is polished in order toreflect the comparison colors into the simultaneous field of vision.

FIG. 140 shows the plate formed as a one-piece body 64 with appropriatetapered recesses so that the rays of the sample image can passtherethrough.

As shown in FIG. 15, the simultaneous field of vision can be producedwith masks 67 and 68, mask 67 serving for blocking the regions in whichthe comparison color is to be placed, whereas mask 68 has openings forthe passage of the rays of the sample color. A pair of photometer prisms65, 66 cooperate with the masks 67, 68, to produce in a plane 43" asimultaneous field of vision similar to that in FIG. 2, but with squaresample color regions. Instead of the photometer prisms 65,66, there maybe employed a set of glass plates 69 which serve to reflect the rays ofthe comparison colors and permit passage therethrough of the rays of thesample color.

FIG. 16 shows another arrangement for producing a simultaneous field ofvision similar to that produced by the apparatus of FIG. 15. In FIG. 16there are shown photometer prisms 70,71 which produce a reflectingsurface 43' which is discontinuous at the locations where the samplecolor is to be passed. This is achieved by contact of the prisms in thesquareshaped non-reflecting regions. The paths of the sample color raysand the comparison color rays are shown by dash-dot arrow lines.

We claim:

1. A visual method of performing color evaluation of a color sample,said method comprising producing, in a plane spaced from a color sample,multiple virtual images of a single small area of said color sample,composing said images in said plane in juxtaposition with a plurality ofindividual separate color comparison places which differ slightly incolor from one another, one for each sample image, forming in said planea simultaneous field of vision in which appear said images and saidcolor comparison places such that the color of the sample can becompared with the colors of the color comparison places, the colors ofthe color comparison places being obtained by the selective combinationof the three color attributes thereof such that the colors of the colorcomparison places differ only slightly from one another, and visuallycomparing the color of the sample images with that of said colorcomparison places and simultaneously varying the color of the latter byselectively varying at least one of the color attributes thereof toachieve visual correspondence of said sample color with one of saidplaces.

2. A visual method of performing color evaluation of a color sample,said method comprising producing in a plane a plurality of separatecolor comparison regions by selectively combining the three colorattributes of the colors in the comparison regions such that said colorsof the comparison regions differ only slightly from one another,producing images of a small area of a color sample and distributing theimages of said sample area in juxtaposition with each comparison regionin said plane whereby there is produced in said plane a simultaneousfield of vision in which the color of the sample can be visuallycompared with that of said comparison regions, and simultaneouslyvarying at least one of the color attributes of the colors of thecomparison regions to establish visual correspondence of the sample withone of said comparison regions.

3. A method as claimed in claim 2, wherein said comparison regions arearranged in said field of vision with a central region and a pluralityin surrounding regions, the visual correspondence of the color of thesample being made with the color of the central region whilesimultaneously the colors of the surrounding regions can be comparedwith the color of the sample to view the magnitude of the color contrasttherebetween.

4. Apparatus for enabling color evaluation of a color sample, saidapparatus comprising first means for producing a plurality of separatecolor comparison images each differing in color slightly from oneanother and for distributing the color comparison images into a planewherein said images form color comparison regions, and second means forproducing a multiplicity of images ofa single small area ofa colorsample, and for applying such images in juxtaposition with said colorcomparison regions in said plane to form in said plane a simultaneousfield of vision of said sample images and said color comparison regions,such that the color of the sample can be compared simultaneously withall the colors of said color comparison regions.

5. Apparatus as claimed in claim 4, wherein said first means forproducing the separate color comparison regions comprises means forcombining the three color attributes of the color at each of said colorcomparison regions, and means for simultaneously varying at least one ofsaid color attributes for all of said regions.

6. A device for visually determining color and color tolerances of asample in natural and artificial light, said device comprising aneyepiece having a field of vision, a light deflecting element, anelement with a reflective multiple discontinuous surface between saidlight deflecting element and the field of vision, said light deflectingelement and multiple discontinuous surface being operatively associatedwith a color sample to produce in said field of vision a plurality ofimages of a small area of said color sample, and means for producing aplurality of color comparison images which differ only slightly in colorfrom one another, the latter said means being operatively positionedrelative to said discontinuous surface such that said color comparisonimages are passed from said multiple discontinuous surface into saidfield of vision in juxtaposition with the sample images.

7. A device as claimed in claim 6 comprising a holder for said colorsample, and means for controlling the amount of light which strikes thesample.

8. A device as claimed in claim 6 comprising means in the path of alight source for selectively controlling illumination of said sample andof the means which produces the color comparison images.

9. A device as claimed in claim 8, wherein said means for controllingillumination comprises a fixed diaphragm plate and a plurality ofmovable diaphragm plates disposed between the source of light and saideyepiece, said diaphragm plates having transparent and opaque areasarranged in such manner that movement of the movable diaphragm platescauses the opaque areas of such plates to eclipse alternately and invarying degrees the transparent areas of the fixed diaphragm plate, saidtransparent areas of the fixed diaphragm plate serving for theillumination of the sample and the means which produces the colorcomparison images.

10. A device as claimed in claim 9, wherein said meansfor producing thecolor comparison images comprises a first chromatic test color surface,and a neutral-gray test color surface, and light deviating units, onefor each test color surface, operatively arranged with a respectivetransparent area of the fixed diaphragm plate for illuminating the testcolor surfaces with the light passing through said transparent areas,and means for superimposing light reflected from said test colorsurfaces to produce the color comparison images.

11. A device as claimed in claim 6, wherein said light deflectingelement has a plurality of inclined surfaces in sideby-side relation toproduce the plurality of separate images of said small area of the colorsample, said multiple discontinuous surface having openings for thepassage of said sample images to the field of vision.

12. A device as claimed in claim further comprising a. secondneutral-gray test color surface and means for superimposing lightreflected from said second neutral-gray test color surface onto eachsaid'sample image, and a further light deviating unit for illuminatingthe second neutral-graytest color surface.

13. A device as claimed in claim 10, wherein said means for producingthe color comparison images further comprises a second chromatic testcolor surface, and an associated light deviating unit, and optical lightmixing means for mixing color images produced by the two said chromatictest color surfaces.

14. A device as claimed in claim 9, wherein the movable diaphragm platesare provided with scales which are in fixed relation with said opaqueareas thereof.

15. A device as claimed in claim 14, wherein said scales are fixedlyattached to said movable diaphragm plates, and wherein said scales andsaid opaque areas are integrally formed of a single layer each.

16. A device as claimed in claim 15, wherein said single layer is metalfoil.

17. A device as claimed in claim 9, wherein the opaque areas of themovable diaphragm plates are so shaped as to permit said alternateeclipsing, whereby optical switching is effected by mixing white and/orblack in the path of light rays of the test colors and alternately inthe path of light rays of the sample.

18. A device as claimed in claim 6, wherein the element with themultiple discontinuous surface is inclined with respect to light raysreflected from the sample, said element being provided with openingswhich are tapered.

19. A device as claimed in claim 6, wherein said multiple discontinuoussurface comprises mirror portions for reflecting the light rays fromsaid sample and opaque portions corresponding to the desired shape ofthe sample images.

20. A device as claimed in claim 6, wherein said element with themultiple discontinuous surface comprises a photometer prism with areflecting surface which is selectively discontinued and a second prismwith intact surfaces, and two inversely shaped masks, respectivelycorresponding to the desired shape of the color comparison regions andthe sample images.

21. A device as claimed in claim 6, wherein said element with themultiple discontinuous surface comprises an arrangement of one set ofglass plates and two inversely shaped masks, respectively correspondingto the desired shape of the color comparison images and the sampleimages and arranged between the eyepiece and the means forproducing thecolor comparison images and the sample.

22. A device as claimed in claim 6, wherein said element with themultiple discontinuous surface comprises a metal piece in combinationwith a tapered central reflector which is mounted on a transparentplate-shaped body, the transparent body being mounted on'a block whichalso carries the metal piece.

23. A device as claimed in claim 22, wherein the metal piece tapers in amanner similar to the central reflector and is integral with the block.7

24. A device as claimed in claim '10, wherein said chromatic test colorsurface is provided with parallel bands of different hues, saidneutral-gray test color surface being provided with parallel bandshaving varying degrees of whiteness, said surfaces being oriented suchthat the bands thereof extend perpendicular to one another.

25. A device as claimed in claim 11, wherein said light deflectingelement is a one-piece body having refractive properties.

26. A device as claimed in claim 11, wherein said light deflectingelement has mirrored reflecting surfaces.

1. A visual method of performing color evaluation of a color sample,said method comprising producing, in a plane spaced from a color sample,multiple virtual images of a single small area of said color sample,composing said images in said plane in juxtaposition with a plurality ofindividual separate color comparison places which differ slightly incolor from one another, one for each sample image, forming in said planea simultaneous field of vision in which appear said images and saidcolor comparison places such that the color of the sample can becompared with the colors of the color comparison places, the colors ofthe color comparison places being obtained by the selective combinationof the three color attributes thereof such that the colors of the colorcomparison places differ only slightly from one another, and visuallycomparing the color of the sample images with that of said colorcomparison places and simultaneously varying the color of the latter byselectively varying at least one of the color attributes thereof toachieve visual correspondence of said sample color with one of saidplaces.
 2. A visual method of performing color evaluation of a colorsample, said method comprising producing in a plane a plurality ofseparate color comparison regions by selectively combining the threecolor attributes of the colors in the comparison regions such that saidcolors of the comparison regions differ only slightly from one another,producing images of a small area of a color sample and distributing theimages of said sample area in juxtaposition with each comparison regionin said plane whereby there is produced in said plane a simultaneousfield of vision in which the color of the sample can be visuallycompared with that of said comparison regions, and simultaneouslyvarying at least one of the color attributes of the colors of thecomparison regions to establish visual correspondence of the sample withone of said comparison regions.
 3. A method as claimed in claim 2,wherein said comparison regions are arranged in said field of visionwith a central region and a plurality in surrounding regions, the visualcorrespondence of the color of the sample being made with the color ofthe central region while simultaneously the colors of the surroundingregions can be compared with the color of the sample to view themagnitude of the color contrast therebetween.
 4. Apparatus for enablingcolor evaluation of a color sample, said apparatus comprising firstmeans for producing a plurality of separate color comparison images eachdiffering in color slightly from one another and for distributing thecolor comparison images into a plane wherein said images form colorcomparison regions, and second means for producing a multiplicity ofimages of a single small area of a color sample, and for applying suchimages in juxtaposition with said color comparison regions in said planeto form in said plane a simultaneous field of vision of said sampleimages and said color comparison regions, such that the cOlor of thesample can be compared simultaneously with all the colors of said colorcomparison regions.
 5. Apparatus as claimed in claim 4, wherein saidfirst means for producing the separate color comparison regionscomprises means for combining the three color attributes of the color ateach of said color comparison regions, and means for simultaneouslyvarying at least one of said color attributes for all of said regions.6. A device for visually determining color and color tolerances of asample in natural and artificial light, said device comprising aneyepiece having a field of vision, a light deflecting element, anelement with a reflective multiple discontinuous surface between saidlight deflecting element and the field of vision, said light deflectingelement and multiple discontinuous surface being operatively associatedwith a color sample to produce in said field of vision a plurality ofimages of a small area of said color sample, and means for producing aplurality of color comparison images which differ only slightly in colorfrom one another, the latter said means being operatively positionedrelative to said discontinuous surface such that said color comparisonimages are passed from said multiple discontinuous surface into saidfield of vision in juxtaposition with the sample images.
 7. A device asclaimed in claim 6 comprising a holder for said color sample, and meansfor controlling the amount of light which strikes the sample.
 8. Adevice as claimed in claim 6 comprising means in the path of a lightsource for selectively controlling illumination of said sample and ofthe means which produces the color comparison images.
 9. A device asclaimed in claim 8, wherein said means for controlling illuminationcomprises a fixed diaphragm plate and a plurality of movable diaphragmplates disposed between the source of light and said eyepiece, saiddiaphragm plates having transparent and opaque areas arranged in suchmanner that movement of the movable diaphragm plates causes the opaqueareas of such plates to eclipse alternately and in varying degrees thetransparent areas of the fixed diaphragm plate, said transparent areasof the fixed diaphragm plate serving for the illumination of the sampleand the means which produces the color comparison images.
 10. A deviceas claimed in claim 9, wherein said means for producing the colorcomparison images comprises a first chromatic test color surface, and aneutral-gray test color surface, and light deviating units, one for eachtest color surface, operatively arranged with a respective transparentarea of the fixed diaphragm plate for illuminating the test colorsurfaces with the light passing through said transparent areas, andmeans for superimposing light reflected from said test color surfaces toproduce the color comparison images.
 11. A device as claimed in claim 6,wherein said light deflecting element has a plurality of inclinedsurfaces in side-by-side relation to produce the plurality of separateimages of said small area of the color sample, said multiplediscontinuous surface having openings for the passage of said sampleimages to the field of vision.
 12. A device as claimed in claim 10further comprising a second neutral-gray test color surface and meansfor superimposing light reflected from said second neutral-gray testcolor surface onto each said sample image, and a further light deviatingunit for illuminating the second neutral-gray test color surface.
 13. Adevice as claimed in claim 10, wherein said means for producing thecolor comparison images further comprises a second chromatic test colorsurface, and an associated light deviating unit, and optical lightmixing means for mixing color images produced by the two said chromatictest color surfaces.
 14. A device as claimed in claim 9, wherein themovable diaphragm plates are provided with scales which are in fixedrelation with said opaque areas thereof.
 15. A device as claimed inclaim 14, wherein said scales are fixedLy attached to said movablediaphragm plates, and wherein said scales and said opaque areas areintegrally formed of a single layer each.
 16. A device as claimed inclaim 15, wherein said single layer is metal foil.
 17. A device asclaimed in claim 9, wherein the opaque areas of the movable diaphragmplates are so shaped as to permit said alternate eclipsing, wherebyoptical switching is effected by mixing white and/or black in the pathof light rays of the test colors and alternately in the path of lightrays of the sample.
 18. A device as claimed in claim 6, wherein theelement with the multiple discontinuous surface is inclined with respectto light rays reflected from the sample, said element being providedwith openings which are tapered.
 19. A device as claimed in claim 6,wherein said multiple discontinuous surface comprises mirror portionsfor reflecting the light rays from said sample and opaque portionscorresponding to the desired shape of the sample images.
 20. A device asclaimed in claim 6, wherein said element with the multiple discontinuoussurface comprises a photometer prism with a reflecting surface which isselectively discontinued and a second prism with intact surfaces, andtwo inversely shaped masks, respectively corresponding to the desiredshape of the color comparison regions and the sample images.
 21. Adevice as claimed in claim 6, wherein said element with the multiplediscontinuous surface comprises an arrangement of one set of glassplates and two inversely shaped masks, respectively corresponding to thedesired shape of the color comparison images and the sample images andarranged between the eyepiece and the means for producing the colorcomparison images and the sample.
 22. A device as claimed in claim 6,wherein said element with the multiple discontinuous surface comprises ametal piece in combination with a tapered central reflector which ismounted on a transparent plate-shaped body, the transparent body beingmounted on a block which also carries the metal piece.
 23. A device asclaimed in claim 22, wherein the metal piece tapers in a manner similarto the central reflector and is integral with the block.
 24. A device asclaimed in claim 10, wherein said chromatic test color surface isprovided with parallel bands of different hues, said neutral-gray testcolor surface being provided with parallel bands having varying degreesof whiteness, said surfaces being oriented such that the bands thereofextend perpendicular to one another.
 25. A device as claimed in claim11, wherein said light deflecting element is a one-piece body havingrefractive properties.
 26. A device as claimed in claim 11, wherein saidlight deflecting element has mirrored reflecting surfaces.